1. Field of the Invention
The present invention relates generally to steel decking used to form flooring and roofing diaphragms of buildings, and more particularly, to a tool for reliably fastening together sidelapped edges of adjacent deck panels when constructing such building diaphragms.
2. Description of the Related Art
Fluted steel deck panels are well known in the art for constructing flooring and roofing of buildings. Examples of such fluted steel deck panels are shown, for example, in U.S. Pat. Nos. 4,186,535 and 4,894,967, both assigned to the assignee of the present application. Such steel deck panels are typically welded to underlying structural support beams. When properly assembled, such fluted steel deck panels provide a cost-effective diaphragm for floors and roofs, as well as relatively high horizontal shear values.
Such fluted steel deck panels typically include first and second opposing sides that extend parallel to the axes of the flutes. One of such sides includes an upwardly-extending male lip. The other of such sides includes a downwardly-directed U-shaped female channel. When two of such deck panels are placed side-by-side across a span of decking, the U-shaped female channel of one panel is engaged over, or overlapped with, the male lip of the adjacent deck panel to interlock the adjacent sides of such panels. This side-lapped joint must then be properly secured to prevent the side of one panel from slipping longitudinally relative to the side of the adjacent panel, and to prevent vertical separation that can result from horizontal loading due to wind, earthquakes, concrete pours, and the like.
Methods for attaching the side-lapped joints of fluted steel deck panels are well known, and include welding, button-punching, sheet metal screws, riveting, and mechanical deformation of the metal forming such side-lapped joint. For example, in U.S. Pat. No. 182,193 issued in 1876, Holeton discloses a method of forming triangular notches in the side-lapped joint and then folding over such triangular notches to interlock the joint. In U.S. Pat. No. 3,641,729, inventor Irvin discloses the use of lip-clenching dies operated by a clinching tool to cut a slit through the side-lapped joint, and to form opposing lobes for securing the side-lapped joint.
In many instances, side-lapped joints of a steel deck diaphragm must be inspected for consistency and integrity before further construction of a building may proceed. To avoid construction delays, it is desirable to form such side-lapped joints in a manner that allows such joints to be inspected quickly and easily, preferably from the top side of the decking.
One apparatus for forming the side-lap attachments which has met with some success is described in U.S. Pat. No. 6,212,932, entitled “Pneumatic Shear For Forming Structural Louvers”. In this patent, a pneumatically-operated tool selectively opens and closes a pair of jaws that are pivotally connected to each other about a common pivot axis. One such jaw includes a single blade having first and second opposing sides forming first and second blunt edges. The second jaw includes two spaced blades that are spaced from each other by the thickness of the single blade on the first jaw, also having blunt edges. Thus, the two spaced blades on the second jaw form a “die” for receiving the single blade on the first jaw when the first and second jaws are pivoted to their closed position. With the jaws in their opened position, the first and second jaws are inserted over a side-lapped seam of a steel deck. The pneumatic tool is then activated to close the jaws toward each other. The single blade of the first jaw passes between the two “die” blades of the second jaw, forming a pair of cuts in the overlapped seam. Further closing of the jaws deforms a central tab in a first direction, while deforming regions on either side of the central tab in the opposite direction. Side-lapped joints formed by use of this apparatus has been shown to securely fasten the side-lapped seams and to satisfactorily resist deformation due to horizontal shear loading.
However, applicant has learned that the apparatus disclosed in U.S. Pat. No. 6,212,932 is subject to breakage when used on heavier gage decking. The single blade provided on the first jaw is subjected to significant stress, as it simultaneously forms two cuts through the overlapped material at the side-lapped seam. In other words, one edge of such single blade forms a first cut in cooperation with a first of the two blades on the second jaw, and the second edge of such single blade forms a second cut in cooperation with the second of the two blades on the second jaw. Because of the significant stress borne by the single blade of the first jaw, such single blade can break, necessitating a stoppage of construction and associated scheduling delays for the user. In addition, such breakage is a significant cost to the tool manufacturer, and related warranty claims detract from the manufacturer's profits.
Accordingly, it is an object of the present invention to provide a punching tool for forming an attachment in an interlocking side-lapped seam of a steel deck structure which provides a solid attachment capable of resisting significant horizontal shear loads.
It is a further object of the present invention to provide such a punching tool which can be operated relatively quickly and easily by a deck installer to attach interlocking side-lapped seams of a steel deck structure.
It is a still further object of the present invention to provide such a punching tool which produces an attachment that can be quickly and easily inspected by an inspector standing atop the assembled steel decking.
Another object of the present invention is to provide such a punching tool having a blade assembly that equalizes the wear on the blades, and which avoids excessive stress on any particular blade, to extend the usable life of the tool.
Still another object of the present invention is to form a sidelapped seam attachment that provides higher shear values by forming an attachment which is more resistant to slippage when subjected to a horizontal load along the longitudinal axis of the sidelapped seam.
Yet another object of the present invention is to provide an improved method of forming such a sidelapped seam attachment.
These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds.